OK, you asked for it...
I tend to agree with Scott in that it would be a good idea to get the bumper and winch on, and load up the truck as if for a trip, and see where everything sits, and how it rides. My guess is that you will indeed want to upgrade the suspension, but if you can afford the in-between time to use this "wait and see" method, it might help you make the right choice on what to get. Having said that, I know most of the time that people can't afford the time to do that. If you have trips planned and want to be done with it, it's much easier just to make a calculated estimate, get all of the parts and have a wrench-fest. Nothing wrong with that.
Regarding Sway-A-Way, here is my .02...
I was SUPER happy with the 2.0 front coilovers I used to have. I got a ton of use out of them and the performance was excellent. I did a rebuild on them at one time, and went through a pair of coils and eventually a set of bushings. But they did their job, and when the parts wore out from lots of service, they were rebuildable. They have since been rebuilt again and are now happily serving on crawler#976's tacoma. (and I miss them!) Since the 2.0's I have gone to the 2.5's and the results have been mixed. The damping performance is great, and they sure do look nice. BUT, the original coil springs that came with them were defective and it took quite a while to get replacements that were correct. Apparently they had a bad batch of coils get assembled on some of their product (this was a year ago and has since been resolved). I am also getting an odd clunking noise from the truck when doing rough trails and the suspension is fully cycling. It appears to be the worst on uphills when the front of the truck is unloaded and the arms allowed to droop more. I can't say for sure that it is the coilovers, but they are suspect until I have some time to get the truck up in the air and do some inspecting. I plan to replace the SAWs with the stock struts and see if I still get the clunking symptom. One other issue I have had is that the adjusting collars were very difficult to turn, even when lubed. The spanner wrench broke, and by the time I had repeatedly adjusted the preload on that first set of defective coils, the collars were toast. The material seemed to be a litte on the soft side, and the tool holes just splayed out. Maybe the plating tolerances, either on the shock can, or on the collars, were just a little thick or something, I don't know. The resistance seemed to come and go as the collar was rotated to various positions on the threads. I had to get them to send me replacement collars when I put the new coils on. The new collars seem to be working okay.
This next issue is just something to keep in mind, and isn't specific to SAW, but can happen with Donahoes also. It just depends on the truck and is more related to the off-chance that the front geometry is just slightly off, as the tolerances for this condition are so close as to make it possible with some trucks and not with others. What happens is that the bottom coil seat (because it is so big to accomodate the larger coil diameter) will contact the banjo-bolt brake fittings under full-droop, full steering lock. This possibility is mentioned in the installation literature. It requires some clearancing of the banjo bolt fitting, either by replacing with an aftermarket piece, or using a rubber mallet to slightly bend the fitting. I'm not certain if this is a condition of the newer Tacomas or not, but my guess is that it might be. It's just something to be aware of. And it is something you don't have to deal with if using the 2.0's
IMO, unless you run the truck really fast and hard for extended mileage, you could save some cash by going with the 2.0's and get just as good of performance. The 2.5's are nice for the extra oil capacity, but I think the 2.0's work just as well. Pay attention to the spring rate for whatever coilover you go with, and don't be afraid to call the mfg. or dealer and ask them to make sure the spring rate is a good match for the final GVW for the front half of your truck. You could always request a different rate if the off-the-shelf doesn't quite jive with your application.
OK, now for the rear shocks...
My Sway-A-Way 2.5" reservoir shocks are incredible. I had them valved specifically for my truck, and they perform very well. You mentioned using SAW for the rear of your truck, but I don't think they make a unit that bolt onto the stock mounts. If you can afford the extra time/money to have some mounts welded to accept the larger/longer shocks, I highly recommend it, especially for these heavy expedition-style trucks we see around here. Smaller shocks will work okay too, but they usually are not rebuildable and will wear out faster, and need to be replaced more often.
I would do a little snooping around on the forums and see if there is any recent feedback on the SAW 2.5 coilovers. I would also send out some emails/PM's to ask people what their recent experience is with them.
As for your leaf springs, I would spend the money to do a full-replacement set tailored exactly to your final GVW requirments.
